Table IV.

Transfusion and iron overload: cardiac, liver and serum iron values.

Cardiac, liver and serum iron values	Age 18–39			Age ≥40			t-test P values
	n	Mean	SD	n	Mean	SD
Age, years	201	27·2	6·1	75	47	6
Serum ferritin, last 12 months	181	2434	2342	71	1251	1554	<0·0001
Serum ferritin by diagnosis
Beta thalassaemia major	130	2395	2083	53	1415	1749	0·003
Beta thalassaemia intermedia	13	2171	2580	17	740·6	510·8	0·007
HbH-Constant Spring	13	2029	2992	1	1215	0
Cardiac iron, MRI T2	124	24·5	13·5	48	30·4	9·2	0·001
Liver iron content
Liver dry weight (mg iron per gram liver weight); MRI or liver biopsy*	128	10·6	10·5	46	4·5	5·7	<0·0001
Liver wet weight (mg iron per gram liver weight): SQUID†	17	4·8	7	6	1·4	0·7	0·06

MRI, magnetic resonance imaging; SD, standard deviation; SQUID, Superconducting Quantum Interfering Device.

^*Liver iron content (mg iron per gram liver dry weight) measured by MRI (n = 126) and by liver biopsy (n = 3; one liver biopsy result not available for analysis) in n = 128 younger adults and by MRI in n = 46 older adults.

^†Liver iron content wet weight measured by SQUID in n = 7 younger adults and n = 6 older adults.